Lagrange Points?

[TwoAngryFigs]

Alright, so I\'ve been messing around with KSP for a week or two, and sharing it with many of my friends. One of my roommates happens to be a Physics major, and he challenged me to park a satellite in one of the Legrange points, if they exist, in the game. After doing a big of snooping, I\'ve discovered that the physics engine in the game does not allow for the L1 and L2 Legrange points to exist. Is there any plan in place to incorporate this into the game?

[Budgie]

About the Space Kraken:

Basicly, as you go farther away from the center of kerbin, strange forces act on you ship. Someone has called it the deep space kraken, so the name has stuck. It has been found to be caused by the games physics engine PhysX, which comes apon problems at 9000m/s, so is therefore not deep space at all. PhysX can also be linked to the reason we don\'t have N point calculations, and therefore no legrange points at L1 and L2, and the transitions between the mun\'s gravity and kerbins gravity (sudden switch over instead of a smooth transition.

I just learned this myself, actually..

[SiliconPyro]

Well, I\'m glad you brought this up since this was one of the personal challenges on my list. It would be great if Lagrange Points were implemented so when the solar system is expanded we could use them to travel to other planets with almost no energy expenditure. Just need to stock up on rations for the brave Kerbanauts.

[TwoAngryFigs]

Haha, I don\'t know if food is the primary concern... Even 4 weeks past liftoff, Jeb still looks as maniacal as ever.

I\'m definitely still interested to see if these will be implemented in later versions.

[Tiberion]

This is a commonly asked question; The answer is.... maybe.

The problem with modeling lagrange points is that it requires KSP to track gravitational forces from more than one body (called an N-body solution)

As the quote said, the game doesn\'t currently do that because its highly inefficient and presents a whole host of other problems on the computational end.

Since having the points modeled doesn\'t provide much gameplay (the biggest benefit being efficient orbital changes for interplanetary flights, which isn\'t in game yet anyway) its a feature they might work on some day, but there are a lot of other features to work on first.

You should go search the Development forum down in the archives for posts by Harvester about Lagrange points and N-body, should find a lot of info about the problems

[Awaras]

Well, the lagrange points for the Earth - Moon system are in a relatively stable position in relation to them, right? It is probably a lot more complicated in cases where there is more than one moon around the planet, but for the \'simple\' three-body problem the five lagrange points are pretty much always in the same position...

So, why not approximate the lagrange points by placing very small, very weak, invisible and immaterial gravity attractors at those points with their own tiny spheres of influence? I know that\'s not how it works in reality, but it would be a 'close enough' solution...

[Tiberion]

Its been suggested, look it up; I believe Harvester said it wasn\'t worth the effort currently, as about all you could do was go sit at the point (or try it, its like trying to stand on one foot on top of a broomstick)

[Awaras]

Its been suggested, look it up; I believe Harvester said it wasn\'t worth the effort currently, as about all you could do was go sit at the point (or try it, its like trying to stand on one foot on top of a broomstick)

Yes, that\'s the thing I never understood about L-points. Everyone talks about them as stable points where you can locate large stations and whatnot, but they are, as you say, \'like trying to stand on one foot on top of a broomstick\' - basically, anything placed there would behave like an inverted pendulum or a marble balanced at the top of a cliff- move just a tiny bit in any direction and you will start to move away from that point. Wouldn\'t it take almost as much energy to balance a station on that point as it would to keep it in any other orbit?

[maltesh]

Yes, that\'s the thing I never understood about L-points. Everyone talks about them as stable points where you can locate large stations and whatnot, but they are, as you say, \'like trying to stand on one foot on top of a broomstick\' - basically, anything placed there would behave like an inverted pendulum or a marble balanced at the top of a cliff- move just a tiny bit in any direction and you will start to move away from that point. Wouldn\'t it take almost as much energy to balance a station on that point as it would to keep it in any other orbit?

L1 (A point between the primary and the satellite), L2 (A point outward from the primary beyond the satellite), and L3 (A point on the opposite side of the primary from the satellite) are unstable points. Any perturbation results in the gravitational forces working out to push the object farther out of the point, resulting in an eventual close encounter with the satellite, and the satellite will enforce its claim to that orbital radius.

L4 and L5 (60 degrees ahead and behind the satellite) are stable. When pushed slightly off those points, the object drifts back into them. That\'s why there are so many asteroids still in Jupiter\'s L4 and L5 points, and why Tethys still has Telesto and Calypso, and Dione; Helene and Polydeuces, to throw out some examples.